ChatGPT Prompt: Create a p5.js sketch that draws four sine waves of different frequencies
and then draws their sum at the bottom of a 400x600 canvas.

Create a function called drawWave(x,y,width,height, freq) that will
draw each of the first four waveforms to be added.

Add a checkbox in each of the first four waveforms called with the label "Include in sum".

When the user check the box in each waveform, add it to the waveform
at the bottom of the canvas.

Put a bounding box around the first four waveforms. Make the height of each of the first four waveforms be 80 and leave a 10 pixel margin between the waveforms.

Label the bottom sum waveform "Sum of Waveforms". Make the label be 16pt.
Make the first four waveforms have a strokeWidth of 1.
Make the strokeWidth of last sum be 4.